This is a placebo-controlled, multiple-dose study of crossover design, consisting of two double-blind treatment phases separated by a 3 to 6 week washout period. Patients meeting the inclusion and exclusion criteria will be assigned randomly to receive either CVT-1 or placebo during the first double blind treatment phase. Patients will receive this double blind study medication for seven days followed by a 3 to 6 week wash out period, then they will receive the alternate double-blind treatment (placebo or CVT-1) for an additional seven days. A diet diary will be maintained during each double blind phase.